Mercedes won the battle against Ferrari in the end, when Valtteri Bottas managed a 1:19.705 on the ultrasoft tyres. That lap time is the fastest time seen at the Circuit de Catalunya eight years, with those lap times last recorded in winter testing of 2009 with the dominant Brawn GP cars. Although Bottas’ 2017 time is still 1.3 seconds adrift of the circuit’s outright fastest lap set by Felipe Massa in 2008 in his Ferrari, the new-generation of cars are already three seconds quicker than this time last winter.

Ferrari may have finished second on the timesheet today, but the Italian team made a bold statement regardless. Bottas’ fastest lap was set on the ultrasoft tyre in the morning. Ferrari responded in the afternoon session with Vettel, he was just 0.247 seconds slower on the soft tyre, a compound two steps harder than the ultrasoft tyre Mercedes ran. Mercedes won the mileage battle however, with Lewis Hamilton’s 95 laps from an afternoon of long running adding to Bottas’ morning haul of 75. It should be noted as ever with pre-season testing we have no way of knowing the fuel loads on either car or their power settings when they set their respective times. But it is clear the competition between Mercedes and Ferrari is hotting up.

“It was reliable already at Fiorano [at the car’s shakedown] but in terms of performance it’s very early to tell,” Vettel reported to the media after the session today. “There is still a lot of work to do.”

Trailing home in third behind the battling Mercedes and Ferrari was the Red Bull of Daniel Ricciardo. Red Bull have had a troublesome start to the test, with a host of technical gremlins curtailing the teams running for the first two days. Today was another though day for the team, as they were 1.5 seconds adrift of the front two teams on the soft tyres. Ricciardo managed 70 laps before those technical gremlins returned, and he was forced to end the day early thanks to an exhaust issue.

It was a mixed day for the other team who have been suffering from pre-season gremlins, McLaren. After two troubled days when the MCL32 spent more time in the garage than out on track, the team started what they hope will prove a recovery in the final five days of testing. The team managed over 70 laps with Fernando Alonso in the car, however, despite completing a short run on the ultrasoft tyres Alonso’s quickest time of 1:22.598 was a full 2.8 seconds off the leading pace. Underlying the team still have a lot to do if they want to challenge the front running teams again. As well as this the team were forced to deny speculation in the Spanish press their relationship with Honda was heading for the rocks, and that they would be dropping the engine before the opening race in Australia.

McLaren are not the only British team having a tough test, as Williams also had a torrid day when Lance Stroll was forced to stop two hours before the end of the day, as a result of the contact he made with the barriers when exiting the tricky turn five. The team had initially moved their driver schedules to give Stroll more time in the car, after his running was cut short on day two following a spin twelve laps in. Things were going well for the rookie teenager, despite a small spin into the gravel trap at turn three in the morning, as he quickly clocked up 98 laps before ending the session in the barriers.

Stroll was not the only driver to cause a red flag with an off today, as Toro Rosso’s Carlos Sainz and Renault’s Jolyon Palmer also suffered spins to trigger red-flag periods. Meanwhile Vettel caused a red flag at the end of the day when his Ferrari broke down on the pit straight.
Testing continues tomorrow at 8AM GMT, with a full report on all the activities of the day on Overtake Motorsport.